[0001] The present invention relates to a flexible pipe body and method of producing the
same. In particular, the present invention relates to the use of polymers including
thermoplastic materials for forming one or more layer of flexible pipe body, and a
method of treatment to enhance the characteristics of the polymer.
Traditionally flexible pipe is utilised to transport production fluids, such as oil
and/or gas and/or water, from one location to another. Flexible pipe is particularly
useful in connecting a sub-sea location (which may be deep underwater, say 1000 metres
or more) to a sea level location. The pipe may have an internal diameter of typically
up to around 0.6 metres. Flexible pipe is generally formed as an assembly of a flexible
pipe body and one or more end fittings. The pipe body is typically formed as a combination
of layered materials that form a pressure-containing conduit. The pipe structure allows
large deflections without causing bending stresses that impair the pipe's functionality
over its lifetime. The pipe body is generally built up as a combined structure including
metallic and polymer layers.
Unbonded flexible pipe has been used for deep water (less than 3,300 feet (1,005.84
metres)) and ultra deep water (greater than 3,300 feet) developments. It is the increasing
demand for oil which is causing exploration to occur at greater and greater depths
where environmental factors are more extreme. For example in such deep and ultra-deep
water environments ocean floor temperature increases the risk of production fluids
cooling to a temperature that may lead to pipe blockage. Increased depths also increase
the pressure associated with the environment in which the flexible pipe must operate.
As a result the need for high levels of performance from the layers of the flexible
pipe body is increased.
Flexible pipe may also be used for shallow water applications (for example less than
around 500 metres depth) or even for on-shore (overland) applications.
[0002] In flexible pipes there are often used polymer layers, such as PVDF (polyvinylidene
fluoride), that may be formed by extrusion. Most polymers will have a certain maximum
allowable strain above which the risk of damage to the material is much greater. In
flexible pipes where a polymer layer lies adjacent an armour layer (such as a polymer
barrier layer adjacent a metallic pressure armour layer), the polymer layer may be
subjected to quite severe non-uniform, highly localised strain. This is because the
armour layer is usually formed from interlocking wires of certain cross section, and
there are certain gaps between adjacent windings. The polymer layer tends to deform
and creep into the gaps when under pressure.
[0003] In accordance with industry regulations, all flexible pipe structures must undergo
a factory acceptance test (FAT) prior to sale. This involves pressurising a pipe bore
with a fluid such as water at 1.5 times the usual pressure of use. The water is thus
a pressurising medium.
[0004] The application of internal pressure (i.e. pressure from within the bore) to the
pipe produces radial expansion in all layers and this is when a polymer layer undergoes
deformation and tends to creep into the gaps of an overlying armour layer. At high
pressures (about 8000 psi / 55 MPa or more), the resultant strain distribution within
the polymer layer can be highly localised at the areas around the gaps, and the polymer
material may deform by cavitation rather than plastic flow. This can in turn result
in the formation of microcrazing or microcracking on the radially inner surface of
the polymer layer. During any subsequent loading (such as the loading experienced
during normal use in transporting production fluids) this microcrazing may then extend
to form longer / deeper cracks throughout the polymer layer. This increases the risk
of failure of the polymer layer and may ultimately lead to loss of pressure containment,
having an adverse effect on the lifetime of a flexible pipe.
AU 672508 B2 discloses a process for manufacturing a flexible tubular conduit, in particular a
flexible tubular conduit comprising at least one tube and/or one jacket made of crosslinked
polyolefin, especially made of crosslinked polyethylene.
US 2008/0283138 A1 discloses a flexible armoured pipe having a center axis and comprising an inner liner
surrounded by at least two armouring layers comprising a radial armouring and an axial
armouring, the radial and axial armouring each comprising at least one armouring layer
of armouring profiles wound with winding angles α
i relative to the center axis, the at least two armouring layers defining an innermost
and an outermost armouring layer relative to the liner wherein the winding angle of
the innermost armouring layer α
innermost is larger than the winding angle of the outermost armouring layer α
outermost, the pipe further comprising at least one fibrous layer surrounding the outermost
armouring layer wherein the fibrous layer comprises at least two fibrous cords wound
on an underlying layer.
According to claim 1, there is provided a method of producing a flexible pipe body
to reduce, inhibit or completely prevent microcrazing, comprising:
providing a tubular length of polymeric material for forming a polymeric layer of
flexible pipe body;
providing a strength layer radially outwards of the polymeric layer; and
treating a radially inner surface of the polymeric layer with a chemical to thereby
cause a change in the modulus of elasticity of the polymeric layer wherein the chemical
has the effect of softening the polymer without dissolving the polymer, wherein the
chemical treatment comprises increasing the elasticity of the polymer in the polymeric
layer, and wherein the chemical is selected from a hydrocarbon oil or fluid, a polar
solvent such as alcohols, non-polar solvents such as benzene or toluene, or ionic
or supercritical liquid solvents.
[0005] Also described herein is a flexible pipe body not forming part of present invention
formed by a process comprising:
providing a tubular length of polymeric material for forming a polymeric layer of
flexible pipe body;
providing a strength layer radially outwards of the polymeric layer; and
treating a surface of the polymeric layer with a chemical to thereby change one or
more physical property of the layer.
The embodiments of the invention provide the advantage that a flexible pipe body is
provided that has been treated to reduce, inhibit or completely prevent microcrazing.
[0006] Certain embodiments not forming part of the invention provide the advantage that
a method of treating a flexible pipe body is provided in which fluid may be used firstly
to treat the pipe body to reduce, inhibit or prevent microcrazing, and then reused
in a factory acceptance test.
[0007] Embodiments of the invention are further described hereinafter with reference to
the accompanying drawings, in which:
Fig. 1 illustrates a flexible pipe body;
Fig. 2 illustrates a riser assembly;
Fig. 3 illustrates a method not forming part of present invention of providing a flexible
pipe body;
Fig. 4 illustrates a cross section of flexible pipe body;
Fig. 5 illustrates apparatus for treating flexible pipe body; and
Fig. 6 illustrates the method according to the invention of providing a flexible pipe.
In the drawings like reference numerals refer to like parts.
Throughout this description, reference will be made to a flexible pipe. It will be
understood that a flexible pipe is an assembly of a portion of a pipe body and one
or more end fittings in each of which a respective end of the pipe body is terminated.
Fig. 1 illustrates how pipe body 100 is formed in accordance with an embodiment of
the present invention from a combination of layered materials that form a pressure-containing
conduit. Although a number of particular layers are illustrated in Fig. 1, it is to
be understood that the present invention is broadly applicable to coaxial pipe body
structures including two or more layers manufactured from a variety of possible materials.
It is to be further noted that the layer thicknesses are shown for illustrative purposes
only.
As illustrated in Fig. 1, a pipe body includes an optional innermost carcass layer
101. The carcass provides an interlocked construction that can be used as the innermost
layer to prevent, totally or partially, collapse of an internal pressure sheath 102
due to pipe decompression, external pressure, and tensile armour pressure and mechanical
crushing loads. It will be appreciated that certain embodiments of the present invention
are applicable to 'smooth bore' operations (i.e. without a carcass) as well as such
'rough bore' applications (with a carcass).
[0008] The internal pressure sheath 102 acts as a fluid retaining layer and comprises a
polymer layer that ensures internal fluid integrity. It is to be understood that this
layer may itself comprise a number of sub-layers. It will be appreciated that when
the optional carcass layer is utilised the internal pressure sheath is often referred
to by those skilled in the art as a barrier layer. In operation without such a carcass
(so-called smooth bore operation) the internal pressure sheath may be referred to
as a liner.
[0009] An optional pressure armour layer 103 is a structural layer with a lay angle close
to 90° that increases the resistance of the flexible pipe to internal and external
pressure and mechanical crushing loads. The layer also structurally supports the internal
pressure sheath, and typically consists of an interlocked construction.
[0010] The flexible pipe body also includes an optional first tensile armour layer 105 and
optional second tensile armour layer 106. Each tensile armour layer is a structural
layer with a lay angle typically between 10° and 55°. Each layer is used to sustain
tensile loads and internal pressure. The tensile armour layers are often counter-wound
in pairs.
[0011] The flexible pipe body shown also includes optional layers of tape 104 which contain
underlying layers and may act as a sacrificial wear layer to help prevent abrasion
between adjacent layers.
[0012] The flexible pipe body also typically includes optional layers of insulation 107
and an outer sheath 108, which comprises a polymer layer used to protect the pipe
against penetration of seawater and other external environments, corrosion, abrasion
and mechanical damage.
[0013] Each flexible pipe comprises at least one portion, sometimes referred to as a segment
or section of pipe body 100 together with an end fitting located at at least one end
of the flexible pipe. An end fitting provides a mechanical device which forms the
transition between the flexible pipe body and a connector. The different pipe layers
as shown, for example, in Fig. 1 are terminated in the end fitting in such a way as
to transfer the load between the flexible pipe and the connector.
[0014] Fig. 2 illustrates a riser assembly 200 suitable for transporting production fluid
such as oil and/or gas and/or water from a sub-sea location 201 to a floating facility
202. For example, in Fig. 2 the sub-sea location 201 includes a sub-sea flow line.
The flexible flow line 205 comprises a flexible pipe, wholly or in part, resting on
the sea floor 204 or buried below the sea floor and used in a static application.
The floating facility may be provided by a platform and/or buoy or, as illustrated
in Fig. 2, a ship. The riser assembly 200 is provided as a flexible riser, that is
to say a flexible pipe 203 connecting the ship to the sea floor installation. The
flexible pipe may be in segments of flexible pipe body with connecting end fittings.
[0015] It will be appreciated that there are different types of riser, as is well-known
by those skilled in the art. Embodiments of the present invention may be used with
any type of riser, such as a freely suspended (free, catenary riser), a riser restrained
to some extent (buoys, chains), totally restrained riser or enclosed in a tube (I
or J tubes).
[0016] Fig. 2 also illustrates how portions of flexible pipe can be utilised as a flow line
205 or jumper 206.
[0017] Fig. 3 illustrates an example in which a flexible pipe body is manufactured. In a
first step S11 a tubular length of polymeric material is provided for forming a polymeric
layer of the flexible pipe body. In this example, the polymeric material is PVDF as
a liner of the pipe body, and is provided by extrusion onto a mandrel in a known manner.
[0018] In a second step S12 a strength layer, which in this case is a pressure armour layer,
is provided over the liner. The pressure armour layer is formed from an elongate strip
of carbon steel having a generally Z-shaped cross-sectional profile. The strip is
formed from a wire rolling process to have corresponding male and female connector
portions such that as the strip is wound over the polymeric layer adjacent windings
interlock.
[0019] A cross section of the polymeric layer 402 and the strength layer 404 is shown in
Fig. 4.
[0020] In a third step S13, a treatment stage is undertaken whereby the polymeric layer
is treated with pressure and heat. Heated water is used to pressurise the bore of
the pipe body, i.e. flushed into and held within the pipe body, and held at pressure.
The pipe body is therefore subject to internal pressurisation. The heat from the heated
water will conduct to the polymeric layer and heat the polymeric layer.
[0021] Fig. 5 illustrates the treatment stage in more detail. A fluid inlet conduit 502
is connected to a heater 504. Water enters the heater 504 and is heated to about 40
degrees in this example. The water then exits the heater and is directed into a first
end 506 of flexible pipe body 501 via a pump member 508 (in the direction of arrow
A). The pipe body 501 is conveniently stored on a reel 510 whilst undergoing the treatment
stage. The heated water is pumped through the pipeline and the pipeline is vented
via a vent 512 to remove air from the system. Water exiting the second end 514 of
the pipe body is re-circulated back to the heater (in the direction of arrow B via
a conduit 516, partly shown) until the temperature throughout the system stabilises
at the predetermined temperature of about 40 degrees. Then, the second end 514 of
the pipe body is closed off via a valve and the pipe body 501 is pressurised using
the pump 508 to a predetermined pressure of 55 MPa and held at that pressure for 2
hours.
[0022] Subsequent to the treatment stage, the valve may be reopened to reduce the pressure
in the pipe body 501 back to ambient, the water cooled to ambient temperature, and
the same water used to perform a Factory Acceptance Test on the pipe body by pressurising
the pipe body to a predetermined pressure. That is, the treatment stage may be immediately
followed by a FAT and the same set up and same fluid used for both stages. Alternatively,
the FAT may be performed at a separate later stage. The pipe body may be emptied of
water, cut down into shorter lengths and the separate lengths then then re-terminated
and subject to a FAT.
[0023] The method of Fig. 3 effectively provides a controlled pressurisation and deformation
of the polymeric layer, without damage to the polymeric layer. The polymeric layer
is somewhat softened by the heat; there will be a thermal gradient across the width
of the layer. The combination of the softening of the material with the application
of pressure causes the polymeric material to move into a closer relationship with
the strength layer, plastically and permanently moving into any gaps 406 that are
present between the windings of the strength layer.
[0024] It has been found that the urging of the polymer into the gaps under certain specified
temperature helps the polymer to flow partially into the gaps, without cavitation
and under a relatively low stress. Once the polymer has moved to the desired amount
into the gaps, as a result of the treatment stage, the polymer remains in that position,
re-hardening after the temperature is removed.
[0025] With the above-described invention, it has been found that surprisingly, areas 408
of the polymeric layer, which may have been subject to high localised strain under
high pressure (from the FAT or in use) in known pipe arrangements due to the proximity
to gaps 406, are not subject to such high strain in further use. That is, even when
the pipe body undergoes high pressure in a FAT or use, the strain levels are not as
high as other known arrangements. This has proved to significantly reduce or completely
prevent any microcrazing in the polymeric layer during its future use after the treatment
stage, including during a FAT and use in transporting production fluids.
[0026] Various modifications to the detailed arrangements as described above are possible.
For example, the polymeric layer may be any layer of the pipe body and is not limited
to the liner or barrier layer. The strength layer may similarly be any layer of the
flexible pipe body such as a pressure armour layer, a tensile armour layer, etc. The
polymeric layer need not be directly adjacent to the strength layer; there may be
intermediate layers such as a sacrificial tape layer. For flexible pipe body with
more than one polymeric layer, the method described above may be employed more than
once so as to treat each of the polymeric layers in turn or concurrently. The treatment
stage may be performed on a barrier layer with a carcass layer present, since a carcass
layer is not fluid-tight and will allow pressurised fluid to flow therebetween to
access the polymeric barrier layer.
[0027] The strength layer may not be a carbon steel wire as described above but may be made
from a stainless steel strip, a reinforced polymer composite material or other such
suitable material, and of any suitable cross section.
[0028] The temperature, pressure, hold time and processing fluid used for the treatment
stage may be chosen according to the particular flexible pipe body materials, design,
and future FAT test pressure. The polymeric layer may be a fluoropolymer such as PVDF,
a polyamide such as PA-12, another material such as polyphenylene sulphide (PPS),
or a combination thereof, and may have additional components such as metallic wires
or nanoparticles dispersed therein.
[0029] Aptly, the temperature used in the treatment stage is between about 30 and 100 degrees
C. The temperature may be between 30 and 90 degrees C, or 30 and 80 degrees C, or
30 and 70 degrees C, or 30 and 60 degrees C, or 30 and 50 degrees C, or 30 and 40
degrees C, for example.
[0030] Aptly, the pressure used in the treatment stage is between about 10 MPa and 350 MPa.
The pressure may be between 50 and 300 MPa, or 50 and 250 MPa, or more aptly 50 and
200 MPa, or 50 and 150 MPa, or 50 and 100 MPa, for example.
[0031] Aptly the duration of the treatment stage when pressure and temperature are applied
may be between 2 minutes and 24 hours, or 5 minutes and 6 hours, or 5 minutes and
4 hours, or 30 minutes and 3 hours, for example.
[0032] Although the description above refers to the use of heated water to pressurise a
pipe body, other fluids can be used. For example steam, oil, or glycol or a mix of
glycol and water may be used in the method described above.
[0033] Rather than a heater to provide fluid at a predetermined temperature, heated fluid
may be provided from a storage unit with an independent or separate heating system,
for example.
[0034] Alternatively, fluid may be provided into a flexible pipe body at ambient temperature,
and then the complete system may be heated from the outside to a uniform predetermined
temperature, and then the internal fluid pressurised.
[0035] Rather than perform the treatment stage with the pipe body in a wound (curved) configuration
on a reel, the treatment stage may alternatively be performed on the pipe body whilst
in a substantially straight configuration, or any other configuration.
[0036] Fig. 6 illustrates the invention in which a flexible pipe body is manufactured. In
a first step S21 a tubular length of polymeric material is provided for forming a
polymeric layer of the flexible pipe body. In this example, the polymeric material
is PVDF as a liner of the pipe body, and is provided by extrusion onto a mandrel in
a known manner.
[0037] In a second step S22 a strength layer, which in this case is a pressure armour layer,
is provided over the liner. The pressure armour layer is formed from an elongate strip
of carbon steel having a generally Z-shaped cross-sectional profile. The strip is
formed from a wire rolling process to have corresponding male and female connector
portions such that as the strip is wound over the polymeric layer adjacent windings
interlock.
[0038] A cross section of the polymeric layer 402 and the strength layer 404 is generally
as shown in Fig. 4.
[0039] In a third step S33, a treatment stage is undertaken whereby the polymeric layer
is treated with a chemical. More specifically, the radially inner surface of the polymeric
layer is soaked with a chemical so as to change at least one physical property of
the layer.
[0040] An example of the treatment stage S33 will now be described. An apparatus similar
to that shown in Fig. 5 may be used for the chemical treatment stage. However, a heater
is not necessary in this example (though may optionally be used).
[0041] A fluid inlet conduit is connected to a first end of flexible pipe body via a pump
member. The pipe body is conveniently stored on a reel whilst undergoing the treatment
stage. Acetone is then pumped through the pipe body. Acetone exiting the second end
of the pipe body may be re-circulated back to the first end of the pipe body. This
acetone flushing is continued for up to 2 hours.
[0042] Subsequent to the treatment stage, the pipe body may then undergo the usual Factory
Acceptance Test by pressurising the pipe body to a predetermined pressure, immediately
or separately. The pipe body may be cut down into shorter lengths and the separate
lengths then subject to a FAT. The polymeric layer may only expand into the gaps of
the strength layer at the time of the FAT. However, the chemical treatment to the
inner surface is sufficient to reduce strain and therefore microcrazing of the layer.
[0043] The method of Fig. 6 effectively provides a treatment stage in which the radially
inner surface of the polymeric layer is exposed to acetone for the predetermined time
length. The exposure causes a change in the stiffness of a portion of the polymeric
layer at the radially inner side, without detrimental degradation of the polymeric
layer. The chemical acts as a semi-solvent, which has the effect to softening the
polymer without dissolving the polymer.
[0044] It has been found that the treatment of the radially inner portion of the polymeric
layer surprisingly has the effect of reducing or preventing microcrazing in the polymeric
layer during later pressurisation of the flexible pipe body. The treatment is applied
in a controlled manner so as to only affect a portion at the radially inner surface
of the polymeric layer. This change to the molecular structure of the surface of the
polymeric layer is sufficient to prevent microcrazing even though the radially outer
portion of the layer (which is the portion that is pushed between gaps in an outer
strength layer) is not treated. It is thought that the chemical treatment increases
the elasticity and toughness of the polymer under pressure at the inner surface sufficiently
to prevent initiation of microcrazing.
[0045] Various modifications to the detailed arrangement as described above are possible.
For example, the polymeric layer may be any layer of the pipe body and is not limited
to the liner or barrier layer. The strength layer may similarly be any layer of the
flexible pipe body such as a pressure armour layer, a tensile armour layer, etc. The
polymeric layer need not be directly adjacent the strength layer; there may be intermediate
layers such as a sacrificial tape layer. For flexible pipe body with more than one
polymeric layer, the method described above may be employed more than once so as to
treat each of the polymeric layers in turn or concurrently. The treatment stage may
be performed on a barrier layer with a carcass layer present, since a carcass layer
is not fluid-tight and will allow pressurised fluid to flow therebetween to access
the polymeric barrier layer.
[0046] The temperature, pressure, hold time and processing chemical used for the treatment
stage may be chosen according to the particular flexible pipe body materials, design,
and future FAT test pressure. The polymeric layer may be a fluoropolymer such as PVDF,
a polyamide such as PA-12, another material such as polyphenylene sulphide (PPS),
or a combination thereof, and may have additional components such as metallic wires
or nanoparticles dispersed therein.
[0047] Although the temperature need not be raised for the treatment stage, in other embodiments
heat could additionally be used, up to 100 degrees C for example.
[0048] Although the chemical may be pumped or flushed through the pipe body sufficiently
for the chemical to come into contact with the polymeric layer (substantially filling
the pipe body bore), the pressure of the chemical may be raised, up to 350 MPa or
a lower amount.
[0049] Aptly the duration of the treatment stage when chemical is applied may be between
2 minutes and 24 hours, or 5 minutes and 6 hours, or 5 minutes and 4 hours, or 30
minutes and 3 hours, for example.
[0050] Although the description above refers to the use of acetone, many chemicals may be
used so as to change a physical property of the polymeric layer. The chemical is selected
from a hydrocarbon oil or fluid, a polar solvent (such as common alcohols), or non-polar
solvents (for example benzene or toluene), or ionic or supercritical liquid solvents.
The physical property may be one or more of shape, modulus of elasticity, stress-strain
relationship, threshold strain for crazing, surface hardness, surface tension, friction
for movement of polymer fibre chains, microstructure of polymer chain distribution,
and density.
[0051] Rather than flushing or pumping a bore of a flexible pipe body with a chemical, the
chemical may be sprayed onto the layer, applied in a transient manner such as by passing
a slug of fluid between two pigs along the length of the pipe body, or applied in
another manner, such as by spraying the outer surface of another adjacent layer, or
by wrapping a doped tape (liquid capsuled tape) against the polymeric layer and applying
pressure to burst the capsules. Alternatively the chemical could be used during the
FAT test itself.
[0052] Although the above describes applying the chemical to the internal surface of the
polymeric layer, additionally, the outer surface of the polymeric layer may be treated.
[0053] Throughout the description and claims of this specification, the words "comprise"
and "contain" and variations of them mean "including but not limited to", and they
are not intended to (and do not) exclude other moieties, additives, components, integers
or steps. Throughout the description and claims of this specification, the singular
encompasses the plural unless the context otherwise requires. In particular, where
the indefinite article is used, the specification is to be understood as contemplating
plurality as well as singularity, unless the context requires otherwise.
1. Verfahren zur Herstellung eines flexiblen Rohrkörpers (100), um Mikrorissbildungen
zu reduzieren, zu hemmen oder vollständig zu verhindern, umfassend:
Bereitstellen einer röhrenförmigen Länge eines polymeren Materials zur Bildung einer
polymeren Schicht (402) des flexiblen Rohrkörpers;
Bereitstellen einer Verstärkungsschicht (404) radial auswärts der polymeren Schicht;
und
Behandeln der radial inneren Oberfläche der polymeren Schicht mit einer chemischen
Substanz, um dadurch eine Veränderung des Elastizitätsmoduls der polymeren Schicht
zu bewirken, wobei die chemische Substanz den Effekt des Weichmachens des Polymers
aufweist, ohne das Polymer aufzulösen, wobei die chemische Behandlung eine Erhöhung
der Elastizität des Polymers in der polymeren Schicht umfasst; und
wobei die chemische Substanz ausgewählt ist als Kohlenwasserstoff-Öl oder -Fluid,
einem polaren Lösungsmittel, wie etwa Alkohole, nichtpolaren Lösungsmitteln, wie etwa
Benzol oder Toluol, oder ionischen oder überkritischen flüssigen Lösungsmitteln.
2. Verfahren nach Anspruch 1, wobei die polymere Schicht ein Fluorpolymer, ein Polyamid
oder ein Polyphenylensulfid oder eine Kombination davon ist.
3. Verfahren nach Anspruch 1 oder 2, wobei der Schritt des Behandelns das Auftragen von
Aceton auf die Oberfläche der polymeren Schicht umfasst.
4. Verfahren nach einem der vorstehenden Ansprüche, wobei das Verfahren ferner das Druckbeaufschlagen
des flexiblen Rohrkörpers auf einen vorbestimmten Druck sowie das Durchführen eines
Werksabnahmetests an dem flexiblen Rohrkörper umfasst.
5. Verfahren nach Anspruch 4, wobei sich die polymere Schicht während dem Werksabnahmetest
in Zwischenräume in der Verstärkungsschicht ausdehnt.
6. Verfahren nach einem der vorstehenden Ansprüche, wobei die Dauer der Behandlungsstufe,
wenn die chemische Substanz aufgetragen wird, zwischen 2 Minuten und 24 Stunden oder
zwischen 5 Minuten und 6 Stunden oder zwischen 5 Minuten und 4 Stunden oder zwischen
30 Minuten und 3 Stunden liegt.
7. Verfahren nach einem der vorstehenden Ansprüche, wobei die Behandlung das Durchtränken
der radial inneren Oberfläche der polymeren Schicht mit der chemischen Substanz umfasst.
8. Verfahren nach einem der vorstehenden Ansprüche, wobei die polymere Schicht eine radial
äußere Oberfläche aufweist, die nicht mit der chemischen Substanz behandelt wird.
9. Verfahren nach einem der vorstehenden Ansprüche, wobei die polymere Schicht eine Mischung
aus Polymer und einem anderen Bestandteil umfasst, wie etwa darin dispergierten Metalldrähten
oder Nanopartikeln.
1. Procédé de production d'un corps de tuyau flexible (100) pour réduire, inhiber ou
empêcher complètement la microfissuration, comprenant les étapes consistant à :
fournir une longueur tubulaire de matériau polymère pour former une couche polymère
(402) du corps de tuyau flexible ;
fournir une couche de résistance (404) radialement vers l'extérieur de la couche polymère
; et
traiter une surface radialement interne de la couche polymère avec un produit chimique
pour provoquer ainsi une modification du module d'élasticité de la couche polymère,
le produit chimique ayant pour effet de ramollir le polymère sans dissoudre le polymère,
le traitement chimique comprenant l'étape consistant à augmenter l'élasticité du polymère
dans la couche polymère, et
le produit chimique étant choisi entre une huile ou un fluide hydrocarboné, un solvant
polaire tel que des alcools, des solvants non polaires tels que le benzène ou le toluène,
ou des solvants liquides ioniques ou supercritiques.
2. Procédé selon la revendication 1, la couche polymère étant un fluoropolymère, un polyamide
ou un poly(phénylène sulfure) ou une combinaison de ceux-ci.
3. Procédé selon la revendication 1 ou 2, le traitement comprenant l'étape consistant
à appliquer de l'acétone sur la surface de la couche polymère.
4. Procédé selon l'une quelconque des revendications précédentes, le procédé comprenant
en outre l'étape consistant à mettre sous pression le corps de tuyau flexible à une
pression prédéfinie et à soumettre le corps de tuyau flexible à un essai d'acceptation
en usine.
5. Procédé selon la revendication 4, la couche polymère se dilatant dans des espaces
à l'intérieur de la couche de résistance pendant l'essai d'acceptation en usine.
6. Procédé selon l'une quelconque des revendications précédentes, la durée de l'étape
de traitement lorsque le produit chimique est appliqué étant comprise entre 2 minutes
et 24 heures, ou 5 minutes et 6 heures, ou 5 minutes et 4 heures, ou 30 minutes et
3 heures.
7. Procédé selon l'une quelconque des revendications précédentes, le traitement comprenant
l'étape consistant à imprégner la surface radialement interne de la couche polymère
de produit chimique.
8. Procédé selon l'une quelconque des revendications précédentes, la couche polymère
ayant une surface radialement externe qui n'est pas traitée avec le produit chimique.
9. Procédé selon l'une quelconque des revendications précédentes, la couche polymère
comprenant un mélange composite de polymère et d'un autre composant tel que des fils
métalliques ou des nanoparticules dispersées en son sein.